It is well known that environmental factors can affect reproductive processes adversely. Primary tobacco smoke (or mainstream-MS-smoke) is known to cause intrauterine growth retardation and has been linked in epidemiological studies to other reproductive problems such as decreased fertility, premature labor, and placenta abruptio. The effects of sidestream (SS) smoke, the major component of environmental tobacco smoke (ETS), on reproduction are not well understood and further animal research in this area is needed. Preliminary data that I have obtained exposing nonpregnant hamsters to SS smoke indicate that the effects on the reproductive system are very different than those seen in hamsters exposed to MS smoke. I have four Specific Aims that I plan to carry out using an in vivo experimental system and exposure to realistic or "physiological" levels of smoke. In Specific Aim #1, I will characterize the effect of time, dose, and length of exposure to SS cigarette smoke on SMC contraction and blood vessel diameter in the nonpregnant uterus. In Specific Aim #2, I will assess the effect of SS smoke on blastocyst transport and implantation in the nonpregnant uterus. In Specific Aim #3, I will characterize the effect of time, dose, and, length of exposure to SS cigarette smoke on SMC contraction and blood vessel diameter in the pregnant uterus. Finally, in Specific Aim #4, I will assess the effect of SS smoke on fetal survival rate and fetal weight. These in vivo experiments will help to clarify the effects of ETS on female reproduction and may help to determine the causal mechanisms underlying our previous observations.